Laser-induced breakdown spectroscopy (LIBS) is a type of atomic emission spectroscopy which uses a highly energetic laser pulse as the excitation source. The laser pulse generates a high temperature micro-plasma on the surface of the sample. After this excitation, light that is characteristic of the elemental composition of the sample is emitted and analyzed within a spectrometer. LIBS has become a very popular analytical method in view of some of its unique features such as applicability to any type of sample, practically no sample preparation, remote sensing capability, and speed of analysis.
Many applications require performing LIBS analysis on liquid samples. One example is identification of metallic wear debris from machinery lubricant, which allows the machinery maintainer to assess the health of the engine or gearbox and identify specific component damage. However, studies have shown that plasma emission is quenched in a liquid sample such as the machinery lubricant, resulting in a reduction in both plasma light intensity and the length of time during which plasma emission can be observed. In addition, some liquid sample is highly transparent to certain laser wavelengths, which raises the threshold of the required laser pulse energy to produce plasma emission. There thus exists a need for a more efficient way to produce and measure laser induced plasma emission in liquid samples.